package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.BloomFilterUtil;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RBloomFilter;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;
    @Resource
    private BloomFilterUtil bloomFilterUtil;
    private RBloomFilter<String> bloomFilter;
    @PostConstruct // 项目启动的时候执行该方法，也可以理解为在spring容器初始化的时候执行该方法
    public void init() {
        // 启动项目时初始化bloomFilter
        List<Shop> shops = this.list();
        bloomFilter=bloomFilterUtil.create("shopList", FILTER_EXPECTED_INSERTIONS,FILTER_FALSE_POSITIVE_RATE);
        for (Shop shop : shops) {
            bloomFilter.add(CACHE_SHOP_KEY+shop.getId());
        }
        log.info("初始化布隆过滤器");
    }
    @Override
    public Result queryByID(Long id) {
        //解决缓存穿透
//        Shop shop =cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById,CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //使用布隆过滤器解决缓存穿透，并使用逻辑过期解决缓存击穿
        Shop shop =cacheClient.queryWithBloomFilterAndLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById,CACHE_SHOP_TTL, TimeUnit.MINUTES,bloomFilter);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
//        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL,TimeUnit.MINUTES);
        //用逻辑过期解决缓存穿透，并用逻辑过期解决缓存击穿
//        Shop shop = cacheClient.queryWithPassThroughAndLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L,TimeUnit.SECONDS);
        if (shop == null) {
            return Result.fail("店铺不存在！");
        }
        // 7.返回
        return Result.ok(shop);
    }

//    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    //用逻辑过期解决缓存击穿问题
//    public Shop queryWithLogicalExpire(Long id){
//        String key= CACHE_SHOP_KEY + id;
//        // 1.从redis查询商铺缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        // 2.判断是否存在
//        if(StrUtil.isBlank(shopJson)){
//            // 3.不存在，直接返回
//            return null;
//
//        }
//        // 4.命中，需要先把json反序列化为对象
//        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
//        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
//        LocalDateTime expireTime = redisData.getExpireTime();
//        // 5.判断是否过期
//        if(expireTime.isAfter(LocalDateTime.now())){
//            // 5.1 未过期，直接返回店铺信息
//            return shop;
//        }
//        // 5.2 已过期，需要缓存重建
//        // 6. 缓存重建
//        // 6.1 获取互斥锁
//        String lockKey = LOCK_SHOP_KEY + id;
//        boolean isLock = tryLock(lockKey);
//        // 6.2 判断是否获取锁成功
//        if(isLock){
//            // 6.3 成功，开启独立线程，实现缓存重建
//            CACHE_REBUILD_EXECUTOR.submit(()->{
//                try {
//                    // 重建缓存
//                    this.saveShop2Redis(id,20L);
//                } catch (Exception e) {
//                    throw new RuntimeException(e);
//                } finally {
//                    // 释放锁
//                    unlock(lockKey);
//                }
//            });
//        }
//        // 6.4 返回过期的商铺信息
//        return shop;
//    }

    //用互斥锁解决缓存击穿问题
    public Shop queryWithMutex(Long id){
        String key= CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            // 3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);

        }
        // 判断命中的是否是空值
        if(shopJson!=null){
            // 返回一个错误信息
            return null;
        }
        // 4.实现缓存重建
        // 4.1 获取互斥锁
        String lockKey =""+id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            // 4.2 判断是否获取成功
            if(!isLock){
                // 4.3 失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            // 4.4 成功，根据id查询数据库
            shop = getById(id);
            // 模拟重建的延时
            Thread.sleep(200);
            // 5.不存在，返回错误
            if(shop == null){
                // 将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"", CACHE_NULL_TTL, TimeUnit.MINUTES);
                // 返回错误信息
                return null;
            }
            // 6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            // 7.释放互斥锁
            unlock(lockKey);
        }
        // 8.返回
        return shop;
    }
    //用缓存空值解决缓存穿透问题
//    public Shop queryWithPassThrough(Long id){
//        String key= CACHE_SHOP_KEY + id;
//        // 1.从redis查询商铺缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        // 2.判断是否存在
//        if(StrUtil.isNotBlank(shopJson)){
//            // 3.存在，直接返回
//            return JSONUtil.toBean(shopJson, Shop.class);
//
//        }
//        // 判断命中的是否是空值
//        if(shopJson!=null){
//            // 返回一个错误信息
//            return null;
//        }
//        // 4.不存在，根据id查询数据库
//        Shop shop = getById(id);
//        // 5.不存在，返回错误
//        if(shop==null){
//            // 将空值写入redis
//            stringRedisTemplate.opsForValue().set(key,"", CACHE_NULL_TTL, TimeUnit.MINUTES);
//            // 返回错误信息
//            return null;
//        }
//        // 6.存在，写入redis
//        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        // 7.返回
//        return shop;
//    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        // 1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        // 2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        // 3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 1.更新数据库
        updateById(shop);
        // 2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if(x == null || y == null){
            // 不需要坐标查询，按数据库查询
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from = (current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current*SystemConstants.DEFAULT_PAGE_SIZE;
        // 3.查询redis、按照距离排序、分页。结果：shopId、distance
        String key=SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()// GEOSEARCH BYLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4.解析出id
        if(results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        //防止分页的from大于记录条数，查询语句in为空
        if(list.size() <= from){
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1 截取从from到end部分
        List<Long> ids=new ArrayList<>(list.size());
        Map<String, Distance> distanceMap=new HashMap<>(list.size());
        list.stream().skip(from).forEach(result->{
            // 4.2 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",",ids);
        List<Shop> shops = query().in("id", ids).last("order by field(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }
}
